Interpretive Summary: Recommendations to increase vegetable and fruit consumption often accompany guidelines for weight loss. A previous study indicated that people who were instructed to count calories lost more weight than those simply instructed to increase vegetable and fruit intake. The objective was to determine if actual vegetable and fruit intakes based on serum carotenoid concentrations, a biomarker for vegetable and fruit intake, were correlated to weight loss and body composition changes. Sixty obese volunteers were enrolled in a 1y weight-loss intervention. Subjects were randomly assigned to one of two groups: calorie reduction group was instructed to restrict total intake by 500 kcal/d and limit fat to 25% and high vegetable group was instructed to increase vegetable intake to 8 servings/d and fruit to 2-3 servings/d. Subjects were provided breakfast and lunch 5 d/wk and taught basic nutrition principles to assist them in meeting dietary goals for the first 3 mo and followed with phone calls of decreasing frequency for the remainder of the year. Vegetable and fruit intake and most serum carotenoid concentrations increased from baseline to 3 mo and remained elevated at 12 mo. Total serum carotenoid concentrations correlated positively with self-reported vegetable intake and combined fruit and vegetable intake. Weight, fat, and %fat were negatively correlated with serum carotenoid concentrations (people who ate more vegetables and fruits, regardless of treatment group, lost more weight). Increased vegetable consumption is an appropriate strategy for weight loss; however, this must still happen within the context of reducing total caloric intake.

Technical Abstract:
Recommendations to increase vegetable and fruit consumption often accompany guidelines for weight loss. A previous study indicated that people who were instructed to count calories lost more weight than those simply instructed to increase vegetable and fruit intake. The objective was to determine if actual vegetable and fruit intakes based on serum carotenoid concentrations were correlated to weight loss and body composition changes. Sixty obese (BMI 30-40 kg/m2) volunteers were enrolled in a 1.5 y weight-loss intervention. Subjects were randomly assigned to one of two groups: calorie reduction group was instructed to restrict total intake by 500 kcal/d and limit fat to 25% and high vegetable group was instructed to increase vegetable intake to 8 servings/d and fruit to 2-3 servings/d. For the first 3 mo, subjects were provided breakfast and lunch 5 d/wk and taught basic nutrition principles to assist them in meeting dietary goals. As a transition, subjects received breakfast and lunch 2 d/wk during the 4th mo and regular phone calls of decreasing frequency for the remainder of the year. Vegetable and fruit intake and most serum carotenoid concentrations increased from baseline to 3 mo and remained elevated at 12 mo. Total serum carotenoid concentrations correlated positively with self-reported vegetable intake and combined fruit and vegetable intake. Changes in weight, fat, and %fat were negatively correlated with serum carotenoid concentrations. Increased vegetable consumption is an appropriate strategy for weight loss; however, this must still happen within the context of reducing total caloric intake.